Anthropic: Claude Fable 5.1
Claude Fable 5.1 improves on Claude Fable 5 across the board, with the biggest gains in agentic coding, long-running agentic workflows, and knowledge work: long code refactors, front-end and visual... Frontier-tier coding and agentic performance Million-token context window Reliable multi-step tool use Strong long-form knowledge work High input and output pricing New version has limited independent benchmark history Autonomous software engineering Long-running research agents Complex tool-using workflows
Specifications
| Lab | Anthropic |
|---|---|
| Context window | 1,000,000 |
| Input price | $10.00/1M |
| Output price | $50.00/1M |
| Release | 2026-09-01 00:00:00 |
Strengths
- Frontier-tier coding and agentic performance
- Million-token context window
- Reliable multi-step tool use
- Strong long-form knowledge work
Weaknesses
- High input and output pricing
- New version has limited independent benchmark history
Best for
- Autonomous software engineering
- Long-running research agents
- Complex tool-using workflows
In Depth: Claude Fable 5.1
Summary
Claude Fable 5.1 is an AI model from Anthropic.
Released 2026-09-01 00:00:00. It supports Text, image, file input and produces Text output, with a context window of 1M tokens. Input pricing is $10.00 per 1M tokens and output is $50.00 per 1M tokens on OpenRouter.